The present invention relates to a corrosion detector for use such as in a marina environment.
Corrosion damage to the hulls and engine components of boats in a harbor can be caused during the electrical interconnection of a group of boats to a dock's AC distribution power system at a modern marina. Electrical currents caused by the appearance of a leakage of DC or AC voltage from the intended conductors can be conducted between the boats in a harbor since the water can become an electrical conductor.
The occurrence of a leakage current between boats interconnected in a harbor or between a boat and the dock can cause damage to some or all of the boats in the harbor as a result of dissolving of the hull by the electrical current. The extent of damage depends upon the amount of metal dissolved. It is known as a result of experiments by Faraday that one ampere of direct current in a conductive medium such as ocean water can dissolve about one gram of metal such as iron in one hour. Continuous corrosion currents in a marina environment can cause serious damage to boats and/or their components.
Corrosion currents which can cause the corrosion damage are DC leakage currents, AC leakage currents, and galvanic currents.
DC leakage corrosion can occur between vessels interconnected electrically between each other and a harbor dock by the harbor wiring. AC leakage current usually comes from a 60 hertz line voltage distributed to connected vessels and cause damage at a lower rate for the same power due to a saturation effect caused by the ions being unable to follow polarity refersals.
Galvanic current can occur between one vessel and nearby vessels similarly connected when the subject vessel has lost all its zinc electrodes. At that time, it begins to draw on zincs (galvanic current) of nearby vessels for galvanic protection. These zincs then dissolve even faster and an avalanche effect occurs that will affect more and more boats over an ever-widening area of the harbor. The rate of damage is much less than that usually due to electrical leakage but it occurs more often.
Although prior art equipment has been developed to provide continuous biasing of hulls which may react to currents of the DC and galvanic type, no equipment has been designed to detect corrosive current interactions between boats and the harbor safety ground electrodes for use to analyze rate of damage and source of the currents. One example of the prior art is an impressed current system, which provides biasing of a hull of a single boat against a submerged electrode, isolated from affecting other boats.
However, a problem occurring with impressed current systems is that they are used to protect against galvanic corrosion in one boat and thus will not respond to leakage currents in the rest of the harbor.
There are various devices designed to detect leakage AC currents in an AC power wiring and load system but are constrained to sense leakage in consumer or industrial applications such as personal safety and AC equipment leakage to the grounding conductor. In either case either the conductors or the grounding current is monitored and the function of the response is to stop the power flowing to the fault. There has generally not been the equipment available that can detect DC as well as AC leakage current occurring in a marina environment.
In view of the above background, it is an objective of the present invention to provide a corrosion detector for use in a marina environment to detect corrosion currents that could cause damage to the hull and equipment of the boats in the harbor.